Steel structural members or studs in the form of c-beams and box 2.times.4's have been used for a number of years in construction work as framing for interior walls and for exterior walls which support, for example, plaster board and exterior sheathing. Such steel studs when used as structural members for exterior walls have a primary drawback in that they readily conduct exterior heat into the air-conditioned building in the summer and do the reverse in winter when the heat loss in cold weather can be so serious that the walls are discolored, called "shadowing", as moisture, including greasy dirt, is deposited on the colder parts of the wall in direct contact with the steel beams supporting the wall.
How serious is this heat loss, or gain, may be seen by considering that a small house of approximately 900 square feet and having dimensions of 32'.times.28' provided with studs 24" on center would have approximately 60 beams or studs about its perimeter. If each stud has dimensions of a 2".times.4", with the 2" sides facing outside and inside there would be a total of steel exposed to the exterior surface. This is a very considerable area (over 8%) interior wall into the house or, in summer, radiating heat into the house.
It is known in the art to provide perforations and openings in metal structural members to receive nails, or to attach insulation, or to reduce heat transmission or a combination thereof and the following U.S. patents illustrate such metal structural members.
In many instances the open slit or punch out permits and in fact invites the passage of air in and out of the stud hollow center to the extent that this convection characteristic of the open slit or perforated opening is counter productive while costing substantially more in manufacturing the closed or abutting slit which can be done simultaneously with the roll slitting required in customary manufacturing of this product.
U.S. Pat. No. 4,016,700 Blomstedt PA1 U.S. Pat. No. 3,841,047 Zinn PA1 U.S. Pat. No. 3,525,189 Nelsson PA1 U.S. Pat. No. 3,482,369 Burke PA1 U.S. Pat. No. 3,158,236 Caligiuri PA1 U.S. Pat. No. 3,129,792 Gwynne PA1 U.S. Pat. No. 2,950,789 Davis Jr. et al PA1 U.S. Pat. No. 1,997,876 Sheldon PA1 U.S. Pat. No. 1,867,449 Ecket et al